A gas such as a greenhouse gas and a stink gas, which exerts bad influence on an environment, is socially coming up as a serious problem. Conventionally, a biological deodorization method is known as a method for eliminating a stink generated when processing garbage, a stink derived from a food factory and a human waste treatment center, or a stink derived from a honey truck. As main stink components, there are hydrogen sulfide, ammonia, methyl mercaptan and so forth. Also, a greenhouse gas, i.e., six kinds of gas, such as carbon dioxide, methane, dinitrogen monoxide, CFC substitute and so forth, is defined as a gas to be reduced in “Law About Promotion Of Global Warming Measure” established in 1998, and an emission reduction of the greenhouse gas is globally promoted. Nevertheless, conventionally, for example, as a method of eliminating carbon dioxide (CO2) defined as the greenhouse gas, only two method are known: one method is to utilize photosynthesis of plants; and the other method is to lay a liquid containing carbon dioxide under the ground.
As a deodorization apparatus utilizing a biological gas decomposition method, an apparatus utilizing photosynthetic bacteria and/or other bacteria and so forth is a representative. The deodorization apparatus utilizing the photosynthetic bacteria has an arrangement wherein a bacteria bed material layer is formed of porous substances, bamboo charcoal substances and/or leaf mold substances and so forth, to which the photosynthetic bacteria activated by lights are adhered, and wherein either a greenhouse gas or a stink gas is made to pass through the bacteria bed material layer under a condition that the bacteria bed material layer is sufficiently illuminated with lights, to thereby eliminate either the greenhouse gas or the stink gas (see: Patent Document 1).
On the other hand, a gas decomposition apparatus utilizing bacteria has an arrangement wherein a bacteria bed material layer is formed of porous substances, bamboo charcoal substances and/or leaf mold substances and so forth, to which the bacteria are adhered, and wherein a gas containing either a greenhouse gas or a stink gas is made to pass through the bacteria bed material layer while feeding a nutrition solution to the bacteria bed material layer, to thereby eliminate the greenhouse gas or the stink gas. In every one of the aforesaid apparatuses, a hydrogen gas lighter than the air and a butane gas heavier than the air are created. Every one of the hydrogen gas and the butane gas is combustible.
Also, for example, as a biological greenhouse gas fixation/elimination apparatus utilizing a biological gas decomposition method, there is the one disclosed in JP-2000-032004 A. This conventional technique is depicted in FIG. 13 in a schematic cross-sectional view. The conventional gas decomposition apparatus comprises a substrate 101a having a recess formed in an upper surface thereof, a schizophycean-culturing-layer feeding pipe (photosynthetic-microorganism-culturing-layer feeding means) 101b for feeding a schizophycean-culturing-layer to the aforesaid recess, a schizophycean-culturing-layer exhausting pipe 101c opening at a bottom of the aforesaid recess, and a schizophycean-culturing-layer exhausting valve 101d for regulating a flow rate of the schizophycean-culturing-layer discharged from the schizophycean-culturing-layer exhausting pipe 101c, and is constituted as a construction-purpose cladding panel (roof cladding panel) having a carbon dioxide decomposition function (see: Patent Document 2).
Further, for example, there is the one disclosed in JP2001-062248 A. This conventional technique is depicted in FIG. 14 in a schematic cross-sectional view. The conventional gas decomposition apparatus has an arrangement wherein an exhaust-gas pH regulating means 214 for regulating a pH of an exhaust gas to fall in the range from pH5 to pH9 which microorganisms like, wherein an exhaust-gas temperature regulating means 216 for regulating a temperature of the exhaust gas to fall in the range from 40° C. to 50° C. which the microorganisms like, are provided in an exhaust-gas introduction pipe 218 in the vicinity of an introduction port 213 thereof, and wherein an organism treatment reaction means is provided in each of decomposition tanks 201 constructed in an exhaust-gas discharging side of the exhaust-gas introduction pipe 218, with the decomposition tanks 201 being arranged side by side in a given number. The exhaust-gas introduction pipe 218 branches so as to be connected to respective exhaust-gas spraying main pipes 220 passing through the decomposition tanks 201, with the exhaust-gas spraying main pipes 220 having exhaust-gas spraying branch pipes 221 in the respective decomposition tanks 201. In each of the decomposition tanks 201, air-injection pipes 224 are provided so as to be longitudinally extended to the bottom of the decomposition tank 201. The exhaust gas is sprayed in a synthetic soil of the organism treatment reaction means provided in each of the decomposition tanks 201, so that contamination substances are absorbed by the organism treatment reaction means. Then, the contamination substances thus absorbed are subjected to a decomposition treatment with the microorganisms.    Patent Document 1: JP-2004-195423 A    Patent Document 2: JP2000-320041 A    Patent Document 3: JP2001-062248 A